Anti-sintering biomass fuel and preparation method thereof

Abstract

The invention belongs to the technical field of biomass fuels, and particularly relates to an anti-sintering biomass fuel and a preparation method thereof.The preparation method comprises the following steps that straw is smashed, then water is added, and cooking treatment is conducted; the straw is dried and subjected to irradiation treatment; the method comprises the following steps: soaking straws in an acid solution, washing with water, and drying; the preparation method comprises the following steps: performing acidolysis treatment on calcite, washing with water, drying, and crushing to prepare pretreated calcite; mixing the straw with the pretreated calcite to prepare a mixture; the mixture is subjected to compression molding, and the biomass fuel is prepared. The straw is pretreated, the content of lignin and other flammable substances in the straw is increased, meanwhile, the content of alkaline metal elements is reduced, the straw is compounded with calcite, and the calcite subjected to acidolysis has a porous structure and can provide an oxygen pore channel structure for the straw, so that sufficient combustion is facilitated; meanwhile, the components in the calcite can improve the melting point of a straw combustion product.

Description

Technical Field

[0001] This invention belongs to the field of biomass fuel technology, specifically relating to an anti-sintering biomass fuel and its preparation method. Background Technology

[0002] Energy is crucial for sustainable social development. Currently, most energy sources are non-renewable, such as oil and coal. The continuous consumption of these energy sources leads to a dwindling surplus, resulting in negative consequences such as price increases and resource competition. This ongoing depletion of these energy sources has spurred significant research into renewable energy. Compared to fossil fuels like oil, renewable energy refers to resources that can be recycled and reused in nature, with biomass fuels being a particularly hot research topic.

[0003] Biomass fuels, including agricultural waste, forestry waste, and organic waste, have attracted much attention due to their high energy storage and relatively low levels of toxic and harmful components in their combustion products. Direct combustion of biomass leads to environmental pollution. Biomass fuels are produced by processing the aforementioned agricultural and forestry wastes into fuel pellets or fuel blocks through processes such as crushing, batching, mixing, and extrusion. These fuel pellets or fuel blocks can be directly burned, yielding higher combustion energy and reducing environmental pollution compared to direct biomass combustion; thus, they represent a green and renewable energy source.

[0004] However, current biomass fuels still have the following problems: incomplete combustion, resulting in lower final heat output, and the presence of more alkaline metals in biomass, which can easily lead to sintering problems and affect the final calorific value. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an anti-sintering biomass fuel and its preparation method, which solves the problems of incomplete combustion and sintering of biomass fuel.

[0006] The present invention is specifically implemented through the following technical solution.

[0007] This invention provides a method for preparing sintering-resistant biomass fuel, comprising the following steps:

[0008] S1. Crush the straw, then add water and cook it at 1.3-1.5 MPa;

[0009] S2. Dry the straw treated in S1 and then subject it to irradiation.

[0010] S3. Soak the straw treated in S2 in an acidic solution, then wash and dry it.

[0011] S4. After acid hydrolysis of calcite, it is washed, dried and crushed to prepare pretreated calcite; the straw treated in S3 is mixed with the pretreated calcite to prepare a mixture.

[0012] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0013] In some embodiments of the present invention, in S1, the straw is one or a mixture of wheat straw, corn straw, sugarcane straw, and rice straw.

[0014] In some embodiments of the present invention, in S1, the length of the straw pulverized is 1-4 mm.

[0015] In some embodiments of the present invention, in S1, the mass ratio of straw to water is 10:3-4.

[0016] In some embodiments of the present invention, in S2, the irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 300-500 kGy, irradiation time of 3-5 min.

[0017] In some embodiments of the present invention, in S3, the acidic solution is one of 0.5-1 mol / L hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

[0018] In some embodiments of the present invention, in step S3, the soaking time in the acidic solution is 30-50 minutes.

[0019] In some embodiments of the present invention, in S4, the acidolysis treatment uses a 0.1-0.5 mol / L hydrochloric acid aqueous solution, and the ratio of calcite to hydrochloric acid aqueous solution is 1 g: 0.5-1 mL.

[0020] In some embodiments of the present invention, in step S4, the calcite has a particle size of 6-10 mm, and after acid hydrolysis for 2-4 minutes, it is washed with water.

[0021] In some embodiments of the present invention, in S4, the mass ratio of the pretreated straw to the pretreated calcite is 1:0.1-0.3.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention first involves crushing straw and then steaming it at high temperature. During steaming, hemicellulose hydrolyzes in a weakly acidic environment, increasing the cellulose and lignin content in the straw solids, which is beneficial for complete combustion and improves calorific value. Next, the straw is irradiated, further breaking down the cellulose and lignin structures, disrupting the internal structure, and increasing the porosity of the straw. The straw is then soaked in an acidic solution, causing the sodium and potassium alkaline metals inside to dissolve, which helps to increase the melting point of the products during subsequent combustion. Calcite is then acid-hydrolyzed to increase its porosity. The treated calcite is then combined with the straw treated in the above process to form a composite material. The porous structure of the calcite increases the porosity of the composite material, facilitating oxygen flow during combustion and allowing the straw to fully contact oxygen for combustion, thus promoting complete combustion. Furthermore, the remaining alkaline metals in the straw can react with the calcite components, increasing the melting point of the straw products, alleviating sintering problems, and increasing calorific value.

[0024] This invention, through the synergistic action of the aforementioned steps, firstly pre-treats the straw to increase the content of flammable substances such as lignin while reducing the content of alkaline metal elements, thus promoting complete combustion; secondly, it combines the straw with calcite, which, after acid hydrolysis, has a porous structure that provides oxygen channels to the straw, further facilitating complete combustion. Simultaneously, the components in calcite can increase the melting point of the straw combustion products. Furthermore, the method of this invention is simple and easy to implement, making it suitable for widespread application. Detailed Implementation

[0025] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and data, but the embodiments are not intended to limit the present invention.

[0026] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0027] There are many reasons for incomplete combustion of biomass fuels, one of which is insufficient contact between oxygen and fuel. Specifically, during the combustion process of biomass fuel, the outer layer, which has sufficient contact with oxygen, often achieves complete combustion, but the inner fuel often suffers from incomplete combustion due to insufficient oxygen penetration. This invention addresses this problem by proposing a solution that allows the prepared biomass fuel to have sufficient contact with oxygen during combustion, thereby improving the fuel's combustion rate. Furthermore, it also addresses the issue of environmental sintering. The specific solution is as follows:

[0028] A method for preparing sintering-resistant biomass fuel includes the following steps:

[0029] S1. Crush the straw, then add water and cook it at 1.3-1.5 MPa;

[0030] During the cooking process, hemicellulose can be hydrolyzed in a weakly acidic environment, which increases the cellulose and lignin content in the straw solids, which is beneficial for fuel efficiency and increases the calorific value.

[0031] S2. Dry the straw treated in S1 and then subject it to irradiation.

[0032] Irradiation treatment further breaks down tissues such as cellulose and lignin, destroys the internal structure, and increases the porosity inside the straw.

[0033] S3. Soak the straw treated in S2 in an acidic solution, then wash and dry it.

[0034] Soaking straw in an acidic solution allows the sodium and potassium alkaline metal elements inside the straw to dissolve, which helps to increase the melting point of the products during subsequent combustion.

[0035] S4. After acid hydrolysis of calcite, it is washed, dried and crushed to prepare pretreated calcite; the straw treated in S3 is mixed with the pretreated calcite to prepare a mixture.

[0036] After acid hydrolysis, the porosity of calcite increases, which facilitates oxygen flow during combustion, allowing the straw to fully contact oxygen for combustion and promoting complete combustion. In addition, the remaining alkaline metals in the straw can react with the calcite components, increasing the melting point of the straw products, alleviating sintering problems, and increasing calorific value.

[0037] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0038] In this invention, in step S1, the straw is one or a mixture of wheat straw, corn straw, sugarcane straw, and rice straw. The length of the crushed straw is 1-4 mm. The mass ratio of straw to water is 10:3-4.

[0039] In this invention, in S2, the irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 300-500 kGy, irradiation time of 3-5 min.

[0040] In this invention, in S3, the acidic solution is one of 0.5-1 mol / L hydrochloric acid solution, sulfuric acid solution, or nitric acid solution.

[0041] In this invention, in step S3, the soaking time in the acidic solution is 30-50 minutes.

[0042] In this invention, in step S4, the acid hydrolysis treatment uses a 0.1-0.5 mol / L hydrochloric acid aqueous solution, with a calcite to hydrochloric acid aqueous solution ratio of 1 g: 0.5-1 mL. The calcite particle size is 6-10 mm. After acid hydrolysis for 2-4 minutes, it is washed with water. The mass ratio of pretreated straw to pretreated calcite is 1:0.1-0.3.

[0043] This invention employs several synergistic steps. On one hand, it pre-treats straw to increase the content of flammable substances such as lignin while reducing the content of alkaline metal elements, thus promoting complete combustion. On the other hand, it combines straw with calcite. The acid-hydrolyzed calcite has a porous structure that provides oxygen channels to the straw, further facilitating complete combustion. Additionally, the components in calcite can increase the melting point of the straw combustion products. Furthermore, the method of this invention is simple and easy to implement, making it suitable for widespread application.

[0044] The present invention will be specifically described below through the following embodiments and comparative examples.

[0045] Example 1

[0046] A method for preparing sintering-resistant biomass fuel includes the following steps:

[0047] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3, and cook at 1.3 MPa.

[0048] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 300 kGy, irradiation time of 3 min;

[0049] S3. Soak the straw treated in S2 in an acidic solution, which is a 0.5 mol / L hydrochloric acid solution, for 30 minutes, then wash with water and dry.

[0050] S4. Calcite (with a particle size of 6-10 mm) is acid-hydrolyzed using a 0.1 mol / L hydrochloric acid aqueous solution at a ratio of 1 g : 0.5 mL. After acid-hydrolyzing for 2 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S3 is then mixed with the pretreated calcite at a mass ratio of 1:0.1 to prepare a mixture.

[0051] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0052] Example 2

[0053] A method for preparing sintering-resistant biomass fuel includes the following steps:

[0054] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:4, and cook at 1.5 MPa.

[0055] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 500 kGy, irradiation time of 3-5 min;

[0056] S3. Soak the straw treated in S2 in an acidic solution, which is a 1 mol / L hydrochloric acid solution, for 50 minutes, then wash with water and dry.

[0057] S4. Calcite (with a particle size of 6-10 mm) is acid-hydrolyzed using a 0.5 mol / L hydrochloric acid aqueous solution at a ratio of 1 g to 1 mL. After acid-hydrolyzing for 4 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S3 is then mixed with the pretreated calcite at a mass ratio of 1:0.3 to prepare a mixture.

[0058] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0059] Example 3

[0060] A method for preparing sintering-resistant biomass fuel includes the following steps:

[0061] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3.5, and cook at 1.4 MPa.

[0062] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0063] S3. Soak the straw treated in S2 in an acidic solution, which is a 0.6 mol / L hydrochloric acid solution, for 40 minutes, then wash with water and dry.

[0064] S4. Calcite (with a particle size of 6-10 mm) is subjected to acid hydrolysis using a 0.4 mol / L hydrochloric acid aqueous solution. The ratio of calcite to hydrochloric acid is 1 g: 0.6 mL. After acid hydrolysis for 3 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S3 is then mixed with the pretreated calcite at a mass ratio of 1:0.2 to prepare a mixture.

[0065] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0066] Example 4

[0067] A method for preparing sintering-resistant biomass fuel includes the following steps:

[0068] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3, and cook at 1.5 MPa.

[0069] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0070] S3. The straw treated in S2 was soaked in an acidic solution, which was a 0.7 mol / L hydrochloric acid solution, for 40 minutes, followed by washing and drying.

[0071] S4. Calcite (with a particle size of 6-10 mm) is subjected to acid hydrolysis using a 0.3 mol / L hydrochloric acid aqueous solution. The ratio of calcite to hydrochloric acid is 1 g: 0.8 mL. After acid hydrolysis for 2 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S3 is then mixed with the pretreated calcite at a mass ratio of 1:0.2 to prepare a mixture.

[0072] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0073] Comparative Example 1

[0074] A method for preparing sintering-resistant biomass fuel, which does not involve high-temperature cooking, includes the following steps:

[0075] S1. Crush the wheat straw into 1-4mm lengths;

[0076] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is...60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0077] S3. Soak the straw treated in S2 in an acidic solution, which is a 0.6 mol / L hydrochloric acid solution, for 40 minutes, then wash with water and dry.

[0078] S4. Calcite (with a particle size of 6-10 mm) is subjected to acid hydrolysis using a 0.4 mol / L hydrochloric acid aqueous solution. The ratio of calcite to hydrochloric acid is 1 g: 0.6 mL. After acid hydrolysis for 3 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S3 is then mixed with the pretreated calcite at a mass ratio of 1:0.2 to prepare a mixture.

[0079] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0080] Comparative Example 2

[0081] A method for preparing anti-sintering biomass fuel, in which the straw is not irradiated, includes the following steps:

[0082] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3.5, and cook at 1.4 MPa.

[0083] S2. The straw treated in S1 is soaked in an acidic solution, which is a 0.6 mol / L hydrochloric acid solution, for 40 minutes, followed by washing and drying.

[0084] S3. Calcite (with a particle size of 6-10 mm) is acid-hydrolyzed using a 0.4 mol / L hydrochloric acid aqueous solution at a ratio of 1 g : 0.6 mL. After acid-hydrolyzing for 3 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S2 is then mixed with the pretreated calcite at a mass ratio of 1:0.2 to prepare a mixture.

[0085] S4. Press the mixture prepared in S3 into shape to obtain biomass fuel.

[0086] Comparative Example 3

[0087] A method for preparing anti-sintering biomass fuel, wherein the straw is not treated in an acidic solution, includes the following steps:

[0088] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3.5, and cook at 1.4 MPa.

[0089] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0090] S3. Calcite (with a particle size of 6-10 mm) is acid-hydrolyzed using a 0.4 mol / L hydrochloric acid aqueous solution at a ratio of 1 g : 0.6 mL. After acid-hydrolyzing for 3 minutes, the calcite is washed, dried, and pulverized to prepare pretreated calcite. The straw treated in S2 is then mixed with the pretreated calcite at a mass ratio of 1:0.2 to prepare a mixture.

[0091] S4. Press the mixture prepared in S3 into shape to obtain biomass fuel.

[0092] Comparative Example 4

[0093] A method for preparing anti-sintering biomass fuel, without acid hydrolysis of calcite, includes the following steps:

[0094] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3.5, and cook at 1.4 MPa.

[0095] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0096] S3. Soak the straw treated in S2 in an acidic solution, which is a 0.6 mol / L hydrochloric acid solution, for 40 minutes, then wash with water and dry.

[0097] S4. Mix the straw treated in S3 with calcite, with a mass ratio of straw to pretreated calcite of 1:0.2, to prepare a mixture;

[0098] S5. Press the mixture prepared in S4 into shape to obtain biomass fuel.

[0099] Comparative Example 5

[0100] A method for preparing sintering-resistant biomass fuel, without the use of calcite, includes the following steps:

[0101] S1. Crush wheat straw to a length of 1-4 mm, then add water at a mass ratio of straw to water of 10:3.5, and cook at 1.4 MPa.

[0102] S2. The straw treated in S1 is dried and then subjected to irradiation treatment. The irradiation source for the irradiation treatment is... 60 Co, irradiation dose of 400 kGy, irradiation time of 4 min;

[0103] S3. Soak the straw treated in S2 in an acidic solution, which is a 0.6 mol / L hydrochloric acid solution, for 40 minutes, then wash with water and dry.

[0104] S4. Press the material prepared in S3 into shape to obtain biomass fuel.

[0105] The materials prepared in the above embodiments and comparative examples were subjected to combustion performance tests. The calorific value was tested according to GB / T213-2008, and the slagging rate was tested according to GB / T 1572-2018. The slagging rate was calculated as follows:

[0106] Slag formation rate = m2 / m1 × 100%

[0107] Where m1 is the total mass of ash residue after burning straw fuel;

[0108] m2 is the mass of slag lumps with a particle size greater than 6mm in the ash.

[0109] The results are shown in Table 1:

[0110] Table 1. Experimental data on the fuels prepared in each embodiment and comparative example.

[0111]

[0112]

[0113] As can be seen from the results in Table 1, the calorific value of Examples 1-4 is significantly higher than that of Comparative Examples 1-5, and the slagging rate of Examples 1-4 is significantly lower than that of Comparative Examples 1-5.

[0114] In Comparative Example 1, no high-temperature cooking process was performed, resulting in a lower content of lignin and other compounds in the straw compared to the examples. This led to incomplete combustion and a lower calorific value. In this invention, the straw is first crushed and then cooked at a high temperature. During the cooking process, hemicellulose undergoes hydrolysis in a weakly acidic environment, increasing the cellulose and lignin content in the straw solids. This promotes complete fuel combustion and improves the calorific value. Comparative Example 1 demonstrates the necessity of the high-temperature cooking step.

[0115] In Comparative Example 2, the straw was not irradiated, resulting in a poorer porous structure compared to the examples. This led to less contact with acid and a lower leaching of alkali metals from the straw, resulting in a higher slag formation rate during combustion. Irradiation treatment further breaks down cellulose and lignin, disrupting the internal structure and increasing porosity within the straw, which facilitates the leaching of alkali metals in subsequent acidolysis steps.

[0116] This invention also involves acid-hydrolyzing calcite to increase its porosity. The treated calcite is then combined with straw that has undergone the same process to form a composite material. The porous structure of the calcite increases the porosity of the composite material, facilitating oxygen flow during combustion and allowing the straw to fully contact oxygen for combustion, thus promoting complete combustion. Furthermore, the remaining alkaline metals in the straw can react with the calcite components, increasing the melting point of the straw products. In Comparative Example 3, the straw was not acid-soaked, resulting in a higher amount of alkaline metals and a higher slagging rate compared to the examples. In Comparative Example 4, no acid-hydrolyzing treatment was performed on the calcite, resulting in less porous structure in the composite material, poorer oxygen-straw contact, and incomplete combustion, thus lower calorific value. In Comparative Example 5, no calcite was used, and its combustion was poor, indicating that the addition of calcite improves straw combustion.

[0117] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing sintering-resistant biomass fuel, characterized in that, Includes the following steps: The straw is crushed, then water is added, and the mixture is steamed at 1.3-1.5 MPa. The cooked straw is dried and then irradiated. The irradiated straw was soaked in an acidic solution, washed with water and dried to obtain pretreated straw. Calcite is acid-hydrolyzed, then washed, dried and pulverized to prepare pretreated calcite; the pretreated straw is mixed with the pretreated calcite to prepare a mixture. The mixture is pressed into shape to obtain biomass fuel.

2. The preparation method according to claim 1, characterized in that, The irradiation source for irradiation treatment is 60 Co, irradiation dose of 300-500 kGy, irradiation time of 3-5 min.

3. The preparation method according to claim 1, characterized in that, The acidolysis treatment uses a 0.1-0.5 mol / L hydrochloric acid aqueous solution, with a calcite to hydrochloric acid aqueous solution ratio of 1 g: 0.5-1 mL.

4. The preparation method according to claim 1, characterized in that, The calcite has a particle size of 6-10 mm, and after acid hydrolysis for 2-4 minutes, it is washed with water.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the pretreated straw to the pretreated calcite is 1:0.1-0.

3.

6. The preparation method according to claim 1, characterized in that, The acidic solution is a 0.5-1 mol / L hydrochloric acid solution, sulfuric acid solution, or nitric acid solution.

7. The preparation method according to claim 1, characterized in that, The soaking time in the acidic solution is 30-50 minutes.

8. The preparation method according to claim 1, characterized in that, The straw is one or a mixture of wheat straw, corn straw, sugarcane straw, and rice straw, and the length of the crushed straw is 1-4 mm.

9. The preparation method according to claim 1, characterized in that, In the cooking process, the mass ratio of straw to water is 10:3-4.

10. The anti-sintering biomass fuel prepared by the preparation method according to any one of claims 1-9.

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